1 / 18

Wide-band Receiver Architecture with Flexible Blocker Filtering Techniques

Wide-band Receiver Architecture with Flexible Blocker Filtering Techniques. AUTHORS: Christian IZQUIERDO Franck MONTAUDON Philippe CATHELIN Andreas KAISER. Outline. Introduction BB-RF Feedback Receiver Negative Feedback Architectures Low pass filter configuration

stacia
Download Presentation

Wide-band Receiver Architecture with Flexible Blocker Filtering Techniques

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wide-band Receiver Architecture with Flexible Blocker Filtering Techniques AUTHORS: Christian IZQUIERDO Franck MONTAUDON Philippe CATHELIN Andreas KAISER

  2. Outline • Introduction • BB-RF Feedback Receiver • Negative Feedback Architectures • Low pass filter configuration • High pass filter configuration • Positive Feedback Architecture • Stability Analysis • Noise Figure • Conclusions

  3. Introduction Software Defined Radio Wide-band LNA + Mixer + Configurable BB filter → Multi-standard application * Ref: ISSCC2006 – R. Bagheri, “An 800MHz to 5GHz SDR receiver in 90nm CMOS” SAW GSM External components to obtain good linearity performances (specially in cellular application) → Duplexer + SAW Filter Wide-band LNA SAW WCDMA SAW LTE

  4. Typical Multi-standard RX-TX On-chip • On-chip circuit • Too many SAW filters SAW Filter: Attenuation@40MHz=45dB  Expensive  Big area  2-3dB signal loss  1 Band = 1 SAW Filter Focus on: Relaxing RF filter requirements * Ref: ISSCC2009 – T. Sowlati – Skyworks Solutions

  5. State of the art – On-chip interferer rejection • Translation feed-forward loop receiver • Linearity enhancement scheme with IM3 cancellation Blockers signals Carrier signal * Ref: ISSCC2008 – E. Keehr * Ref: JSSC2007 – H. Darabi Requirement of a very high linearity LNA!!!

  6. BB-RF Feedback Receiver Wide-band Mixer Ampli BB Filter ADC LNA (Gmix) (Gamp) GLNA I/Q Path FLO gOTA Feedback Feedback Feedback Current Mixer (Gmix) Filter (Gfil) I/Q Path Idea: Translate BB filtering to RF input thanks to the feedback • RF Filtering at the LNA input Blocker signals are attenuated

  7. Model of BB-RF Negative Feedback Receiver G: forward voltage gain gR: feedback loop transconductance gain RF Filtering at the LNA input Matching to the antenna impedance in-band. Mismatching out-band RF Central frequency = FLO

  8. LPF fLO fBB fRF fRF Low Pass filter configuration – Theorical Analysis Mixer Ampli (Gmix) (Gamp) Blocker signal fRF Carrier signal LNA + Voie I/Q FLO - gOTA LPF FLO Ampli Feedback V / I Mixer(Gmix) I/Q Path Openloop: ZIN=ZLNA > ZANT Closeloop: ZIN(fLO) = ZANT Input Impedance Mathematical expression

  9. ZIN=50Ω LPF Configuration – Simulation results Input Impedance Input Voltage ZLNA=1KΩ Over voltage • Matching in-band (ZIN=50Ω) and mismatching out-band (ZIN>50Ω) • Over voltage for out-of-band signals in LNA input

  10. HPF fLO fBB fRF High Pass filter configuration – Theorical Analysis Mixer Ampli (Gmix) (Gamp) fRF Blocker signal Carrier signal LNA + Voie I/Q FLO - FLO gOTA HPF Ampli Feedback V / I Mixer(Gmix) I/Q Path fRF Openloop: ZIN=ZLNA > ZANT (Image Frequency) Closeloop: ZIN(fLO) = ZANT Input Impedance Mathematical expression

  11. HPF Configuration – Simulation results Input Impedance Input Voltage ZLNA=1KΩ ZIN=50Ω Att=2.5dB • Matching in-band (ZIN=50Ω) and mismatching out-band (ZIN<50Ω) • Image Frequency of first mixer superposed with BB signal. • Attenuation is not good (<3dB)

  12. LPF fLO fBB fRF fRF fRF Positive Feedback Architecture Mixer Ampli LNA (Gmix) (Gamp) Blocker signal Carrier signal + GLNA + Voie I/Q FLO FLO gOTA LPF Ampli Feedback V / I Mixer(Gmix) I/Q Path Openloop: ZIN=ZLNA < ZANT In-band signal enhanced Input Impedance Mathematical expression:

  13. Results simulation Input Impedance Input Voltage ZLNA=10Ω ZLNA=3Ω Att=19dB • Matching in-band (ZIN=50Ω) and mismatching out-band (ZIN<50Ω) • Good attenuation. It depends of initial ZLNA

  14. Stability Analysis Feed-back Gain: Stability condition For f=fLO: S2=-1.07 S1=-0.88 (-1,0) • Stable for S1 • Unstable for S2

  15. Noise Figure X1 A: forward voltage gain B: feedback loop voltage gain FA: NF of forward path FB: NF of feedback loop + XA XS XO A + B XB X2 Feedback path contribution Forward path contribution

  16. Application Example For ZLNA=3: If A=36dB  gR=4.9mS, B=gR*ZIN(fLO) = 0.245 With these values, S=-0.88>-1 System is stable!!! NFCL to be compared to NF of SAW+ Typical Receiver

  17. Conclusions • BB-RF Positive Feedback Receiver • Channel Filtering in RF • Good blocker rejection (19 dB) • Adjustable BW and center frequency • Attenuation depending on Design Trade-offs: ZLNA, NF and Stability • Though not yet sufficient to remove the SAW filter, this technique • Relaxes filtering requirements • Allows more compact and less expensive receivers

  18. Thank you!!!

More Related